Abstract
The strong control of temperature on the timing of plant phenology is
expected to cause substantial shifts in flowering times under climate
change. Yet, the sensitivity of flowering phenology in dryland regions
to climate change, and the potential implications for community
composition, remain largely unexplored. Here, we investigate the effects
of climate warming and nitrogen addition on flowering phenology of four
C3 plants and two C4 plants and explore
cascading effects on shifts in C3 vs C4plant dominance in a 17-year field experiment in a desert steppe. Across
the last 10 years of the experiment (2013–2022), we found that warming
had a greater effect on phenological shifts in C3 than
in C4 plants.
Warming significantly advanced
the flowering time of C3 plants by 4.3 ± 0.1 days and of
C4 plants by 2.8 ± 0.1 days. Warming also reduced the
duration of flowering by 1.8 ± 0.1 days and decreased the dominance of
C3 plants compared to C4 plants
(P <0.05). Nitrogen addition extended the duration of flowering
of C4 plants by 3.4 ± 0.2 days and increased their
relative dominance, while having no effect on C3 plants.
Structural equation models highlighted that these phenological responses
were influenced by soil temperature and soil water availability. Our
results show the divergent phenological responses between
C3 and C4 plants under global changes,
predicting shifts in dominance between these plant types in temperate
dryland ecosystems.